I've been looking into the different kind of locks available, and came upon this short documentary about bike thefts in London. Seems that just about any lock on the market can be easily beaten by a large enough set of bolt cutters. So I was trying to think of a better system, and I thought of something: Why not have locks that are built into the bike itself? Something that locks out the drive train in some way?

It seems that in the majority of thefts, the thieves are riding away on the bike. From about 10 minutes of pondering the question, it seems like a small hole could be placed in the crank axle without compromising the strength too much, and then you could incorporate the locking mechanism into the down tube. When the bike is locked, the cranks can no longer turn.

Searching on the internet yielded no results for locks that lock the drive train of the bike. Is it just an unworkable idea, or has nobody thought of it until now?

You would still have to lock the bike to a rack to ensure that someone doesn't just carry it away or put it on the back of a truck. But it would make the bike that much less of a target if the thief knew that such a system was in place.

haha +1 for the image of shifting the bike into and out of "park"
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BabuAug 12 '11 at 0:19

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Just thought of an even simpler idea, that required no modifications to the bike. Take a small u-lock, and lock the crank arm to the down tube. You could defeat this by removing the pedal, but many bike thiefs might be deterred by the time it would take to do this, and move onto the next bike.
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KibbeeAug 12 '11 at 0:28

@Kibbee - I like that idea. Removable pedals (of the sort you sometimes see for folding bikes) might do some of the same thing. Also, some platform pedals might allow you to thread a u-lo k through the pedal and around the frame.
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Neil FeinAug 12 '11 at 1:51

I've been thinking of this for some time. Had 2 bikes stolen right in front of the store. Both locked with 1.5cm cable. Thought of the same idea as above because I always used to steering lock my motorcycle. I realize picking up a motorcycle is a bit more difficult, though not unheard of. I use a U-bolt now, but often times it isn't able to attach to a standard. That worries me. I've put too much custom work, blood, sweat and tears to leave it anywhere out of sight.
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user13756Sep 13 '14 at 21:39

3 Answers
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Raleigh fitted a steering lock to many of their bikes up until the 1970's:

I have got a bike with one but I would not use it without a secondary lock to a fixed object. Neither would I use what you are looking for, and for the same reasons! It is a solution looking for a problem that is not practical in the real world. You don't want someone taking you bike away so they can strip it for parts.

Note that the Raleigh people could have put their immobiliser on the bottom bracket if they wanted to, or even in the hub gears. The advantage of the steering lock is that a thief on a bike with locked steering is likely to crash.

Actually, a system of internal cables that locked the fork and crank might make sense (in addition to a lock to a fixed object). But I wonder if it wouldn't make more sense to add a Lojack to the bike.
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Daniel R HicksAug 14 '11 at 12:18

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Interesting concept. Basically anything the prevented normal operation of the bike would be a plus. I've even heard people say fixies are a deterrent simply because not a lot of people know how to ride them. Won't stop the professional thief, but will stop "transportation thieves". In the video I linked to in the post they hook up a simple GPS Tracker under the saddle. I wonder how much such a device would cost. Certainly no more than some of the expensive locks on the market. Maybe have an RFID system like they do with pets. Would help of the LBS checked before fixing bikes.
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KibbeeAug 14 '11 at 15:39

Wheel locks are an implementation of this idea. They simply prevent the rear wheel from turning, which is effectively the same thing.

Again, any thief with large enough bolt cutters will be able to effectively sidestep the problem without hassle. But worse than that, the odds of your bike being stolen while being immobilized like this are still orders of magnitude higher than locking your bike to something with a U-lock. Any thief can merely pick up the bike and run off with it (which is more doable than you'd think) or toss it into the bed of a pickup and be gone.

And that's simply what it comes down to. Locking the drivetrain doesn't provide any additional mechanism that a prepared thief wouldn't already be able to work around, and, while better than leaving your bike totally unlocked, is still far less safe than a U-lock.

I was thinking, you'd still need the u-lock, so they can't just toss the bike in the back of a truck and worry about the bike later, but some kind of extra deterrent mechanism.
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KibbeeAug 12 '11 at 2:03

If they've cut through a U-lock, what chance does your drivetrain lock stand? And it might be awkward riding a bike, anyway, with bolt cutters large enough to take out a U-lock.
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Stephen TousetAug 12 '11 at 3:04

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If the drive train lock was internal to the frame, it would be much harder to break without damaging the bike. They would have to resort to picking the lock, which is a much more specialized skill, which many bike thieves do not have.
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KibbeeAug 12 '11 at 16:06

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The only way I can see that it could be entirely internal to the frame would be if it stopped the rotation of the bottom bracket.
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Stephen TousetAug 12 '11 at 18:31

basically what I was thinking. Wouldn't be an impossible task.
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KibbeeAug 12 '11 at 21:21

You could put a padlock through the crank for extra security, so when the crank is turned it would hit the derailer or get trapped in the chain. Extra security of any kind will reduce the likelyhood of theft!